1. Field of the Invention
The present invention is directed to an optical coupling device for coupling integrated optical components formed on separate substrates and for providing height compensation.
2. Prior Art
If monolith technology is not used in the production of integrated optical circuits, the waveguide and substrate materials for each of the components may be optimally selected for each component according to the function of the component and the desirability of making this selection has been increasing recently. However, the waveguides of each of the component substrates must be optimally connected to one another on a common base substrate. A typical example for the necessity of waveguide connection of separate component substrates is present in the connecting of the waveguide laser with an external waveguide modulator. For example, the waveguide laser is produced in an epitaxial Nd.sup.3+ : YAG layer on a sapphire component substrate and the waveguide modulator is an epitaxial LiNbO.sub.3 layer on a suitable substrate of another crystal material. The laser and the modulator must then be coupled together.
Since the thickness of the waveguides, which are used, is in the order of magnitude of micrometers and the mode behavior is not to be disturbed by undefined coupling points, for example such as light guiding lacquer drops or other immersion materials, the connecting of integrated optical components has been technologically very expensive. Thus, an optimum connection of the waveguide pieces, which have been formed on various component substrates, could, up to the present, only be achieved in the following process. Each of the component substrates were cut from a common block, flat polished on both sides to a smoothness of .lambda./10 and then subsequently wrung onto a base substrate which was also polished flat to a smoothness of .lambda./10.
For the production of this type of aligned waveguide connection in hybrid technology, a considerable technological and labor expenditure was necessary. While the labor costs and technological costs are acceptable for fundamental research in a laboratory, these costs in both time and labor are not acceptable for commercial applications of the hybrid integrated optical components.